The optimal reproduction of multichannel audio content (e.g., stereo audio, 5.1 channel audio, 7.1 channel audio) imposes restrictions on loudspeaker placement relative to a listening position. For instance, some audio systems recommend preferred angles and distances between loudspeakers to achieve optimal performance. These measures ensure that the spatial imaging produced by loudspeakers is in line with the intent during a mixing phase.
However, in a practical situation it is not always possible (e.g., room layout constraints) or desired (e.g., aesthetical preferences) to place loudspeakers at their recommended distances and angles. To compensate for non-ideal placement, some surround sound receivers implement a gain and delay compensation technique. This technique aims at ensuring that the sounds from all loudspeakers reach a listening position at the same time and level. More advanced systems also offer the possibility to compensate for timbral differences between loudspeakers by including an equalization system. However, even when time, level and spectrum are equal at a listening position, some audible differences remain, which are the result of inconsistent direct-to-reverberant ratios from sound produced by each loudspeaker.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.